JP4093569B2 - Color image forming apparatus - Google Patents

Description

【００９６】
スキューｄＳｑｙ：
リアｒ側の直交マークＭＡｙｒとフロントｆ側の直交マークＭＡｙｆの中心点位置の差
ｄＳｑｙ＝（Ｍｂｆ−Ｍｂｒ）。
【００９７】
主走査線長のずれ量ｄＬｘｙ：
リアｒ側の斜交マークＭＢｙｒとフロントｆ側の斜交マークＭＢｙｆの中心点位置の差（Ｍｆｆ−Ｍｆｒ）から、スキューｄＳｑｙ＝（Ｍｆｆ−Ｍｆｒ）を減算した値

【００９８】
他の、ＣおよびＭの作像ずれ量は、上記Ｙに関する算出と同様にして算出する（Ａｃｃ，Ａｃｍ）。Ｂｋも大略では同様であるが、この実施例では、副走査方向ｙの色あわせはＢｋを基準にしているので、Ｂｋに関しては、副走査方向の位置ずれ量ｄｙｋの算出は行わない（Ａｃｋ）。
【００９９】
図８に示すずれの調整（ＤＡＤ）では、ＭＰＵ４１は、次のように、各色の作像ずれ量を調整する。Ｙのずれ量調整（Ａｄｙ）を、具体的に次に示す。
【０１００】
副走査ずれ量ｄｙｙの調整：
Ｙトナー像形成のための画像露光（潜像形成）の開始タイミングを、基準のタイミング（ｙ方向）から、算出したずれ量ｄｙｙずらして設定する。
【０１０１】
主走査ずれ量ｄｘｙの調整：
Ｙトナー像形成のための画像露光（潜像形成）の、ライン先頭をあらわすライン同期信号に対する、書込みユニット５の露光レーザ変調器への、ライン先頭の画像データの送出タイミング（ｘ方向）を、基準のタイミングから、算出したずれ量ｄｘｙ分ずらして設定する。
【０１０２】
スキューｄＳｑｙの調整：
書込みユニット５の、感光体ドラム６ｂに対向してＹ画像データで変調したレーザビームを反射して感光体ドラム６ｂに投射する、ｘ方向に延びるミラーのリアｒ側は支点支持され、フロントｆ側が、ｙ方向に摺動可のブロックで支持されている。このブロックをパルスモータとスクリューを主体とするｙ駆動機構で、ｙ方向に往，復駆動してスキューｄＳｑｙを調整できる。「スキューｄＳｑｙの調整」では、このｙ駆動機構のパルスモータを駆動して、ブロックを基準のｙ位置から、算出したスキューｄＳｑｙに相当する分駆動する。
【０１０３】
主走査線長のずれ量ｄＬｘｙの調整：
ライン上に画素単位で画像データを割りつける画素同期クロックの周波数を、基準周波数×Ｌｓ／（Ｌｓ＋ｄＬｘｙ）に設定する。Ｌｓは基準ライン長である。
【０１０４】
他の、ＣおよびＭの作像ずれ量の調整は、上記Ｙに関する調整と同様にして調整する（Ａｄｃ，Ａｄｍ）。Ｂｋも大略では同様であるが、この実施例では、副走査方向ｙの色あわせはＢｋを基準にしているので、Ｂｋに関しては、副走査方向の位置ずれ量ｄｙｋの調整は行わない（Ａｄｋ）。次回の「色合わせ」まで、このように調整した条件でカラー画像形成を行う。
【０１０５】
−第２実施例−
第２実施例のハードウエア構成は、上述の第１実施例と同一である。しかし第２実施例では、ＭＰＵ４１は、図１５に示す「色合せ」（ＣＰＡ）を行う。この「色合せ」（ＣＰＡ）の中のステップ３１〜３７の内容は、図８に示す同一符号のものと同様である。この第２実施例では、「テストパターンの形成と計測」ＰＦＭの実行回数ｎが設定値ｄを越えると、第２態様の「テストパターンの形成と計測」ＰＦＭａを実行する。このＰＦＭａでは、先行して実行した「テストパターンの形成と計測」の中の「マーク中心点位置の算出」で得た接続痕中心点位置を参照して、接続痕にマークが触れない（形成するマークに接続痕が接触しない）タイミングを算定して、該タイミングでマークの形成を開始して、転写ベルト１０上に、図１７に示すように、リアｒ，センターｃおよびフロントｆのそれぞれに、スタートマークならびに８セットのテストパターンを含むｒマーク，ｃマークおよびｆマークの組を形成して、光センサ２０ｒ，２０ｃ，２０ｆでマークを検出して、マーク検出信号Ｓｄｒ，Ｓｄｃ，ＳｄｆをＡ／Ｄコンバータ３６ｒ，３６ｃ，３６ｆでデジタルデータすなわちマーク検出データＤｄｒ，Ｄｄｃ，Ｄｄｆに変換して読みこむ。そして、マーク（Ｓｄｒ，Ｓｄｃ，Ｓｄｆ）の中心点位置を算出する。
【０１０６】
次の「パターンの検証」ＳＰＣａでは、まず「ｒマークの検証」で、中心位置算出値があるｒマークそれぞれのｙ幅を算出し、ｙ幅が設定幅範囲内かをチェックして、設定幅範囲内のマークのみの中心位置を、該マーク宛にｒメモリに登録する。この「ｒマークの検証」の内容は、次に説明する「ｆマークの検証」の内容と同様である。
【０１０７】
次に図１６を参照すると、ＭＰＵ４１は、「ｆマークの検証」（８０）で、中心位置算出値があるｆマークそれぞれのｙ幅を算出し（８１，８２）、このｙ幅が設定幅範囲内かをチェックして（８４）、設定幅範囲内のマークのみの中心位置を、該マーク宛にｆメモリに登録する（８５）。
【０１０８】
更に、ＭＰＵ４１は、「ｃマークの検証」（１１０）で、中心位置算出値があるｃマークそれぞれのｙ幅を算出し（１１１，１１２）、このｙ幅が設定幅範囲内かをチェックして（１１４）、設定幅範囲内のマークのみの中心位置を、該マーク宛にｆメモリに登録する（１１５）。
【０１０９】
次にＭＰＵ４１は、ｒ，ｃ，ｆメモリに書きこんだマーク中心点位置データ群が、図１７に示すマーク分布相当の中心点分布であるかを検証し、ｒマーク，ｃマークおよびｆマークの検出情報を図１７に示すセット対応にグループ化する（９０，１００，１２０）。ここで、図１７に示すマーク分布相当から外れるデータは、セット単位で削除して、図１７に示すマーク分布相当の、分布パターンとなるデータセットのみを残す。すべて適正な場合は、リアｒ側に８セット、センターｃに８セット、フロントｆ側にも８セットのデータが残る。
【０１１０】
ここでＭＰＵ４１は、リアｒ側のセット数，センターｃのセット数およびフロントｆ側のセット数のそれぞれが、設定範囲内（ｂ以上ｃ以下）かをチェックする（３３ａ）。
（１）リアｒ側のセット数およびフロントｆ側のセット数のいずれもが設定範囲内であると、第１態様指定情報を生成して、次に進み、第１実施例と同じ平均パターンの算出，ずれ量の算出をそれぞれＭＰＡａおよびＤＡＣａで実行してから、第１実施例と同じ内容のずれの調整ＤＡＤに進む。
（２）しかし、リアｒ側のセット数が設定範囲を外れ、センターｃおよびフロントｆ側のセット数の両者が設定範囲内であると、第２態様指定情報を生成して、次に進み、センターｃおよびフロントｆ側のマークセットに基く平均パターンの算出，ずれ量の算出をそれぞれＭＰＡａおよびＤＡＣａで実行してから、第１実施例と同じ内容のずれの調整ＤＡＤに進む。
（３）フロントｒ側のセット数が設定範囲を外れ、センターｃおよびリアｒ側のセット数の両者が設定範囲内であると、第３態様指定情報を生成して、次に進み、センターｃおよびリアｒ側のマークセットに基く平均パターンの算出，ずれ量の算出をそれぞれＭＰＡａおよびＤＡＣａで実行してから、第１実施例と同じ内容のずれの調整ＤＡＤに進む。
（４）リアｒ側，センターｃおよびフロント側ｆの少なくとも２者のマークセット数が設定範囲を外れているときには、「テストパターンの形成と計測」の回数ｎを１インクレメントして、また「テストパターンの形成と計測」ＰＦＭａに進む。しかし、回数ｎが設定値ｉに達したときには、レジスタＦＡＰに、色合せ自動実行を禁止するデータ１を書込み（３８−３６）、転写ベルト異常，クリーニング又は交換要、を表す情報を操作ボード６１０の表示装置６１５に表示する（３７）。そして、「色合せ」ＣＰＡを終了する。この場合には、色ずれ調整は行われない。
【０１１１】
【発明の効果】
色合せが、指示入力があった場合のみならず、所定の条件が成立したときに自動的に実行されるので、色ずれのないカラー画像を安定して形成できる。そして、例えばマーク形成面の劣化によりマーク検出精度が低下すると、色合せの自動起動が制限されるので、色合せの実行によってカラー画像形成装置が使えない時間すなわちダウンタイムの長期化が防がれる。
【図面の簡単な説明】
【図１】 本発明の一実施例であるフルカラー複写機の外観を示す正面図である。
【図２】 図１に示すカラー複写機の画像データ処理システムの概要を示すブロック図である。
【図３】 図１および図２に示すプリンタ１００の作像ユニットＰＴＲの作像機構の概要を示す拡大縦断面図である。
【図４】 図２に示す転写ベルト１０の平面図であり、その表面に形成される各色マークを模式的に示す。
【図５】 図２に示す転写ベルト１０に形成するマークの分布を示す拡大平面図である。
【図６】 図２に示すプロセスコントローラ１３１の一部分の構成を示すブロック図である。
【図７】 図６に示すマイクロコンピュータ（ＭＰＵ）４１のプリント制御の概要を示すフローチャートである。
【図８】 図７に示す「色合わせ」ＣＰＡの概要を示すフローチャートである。
【図９】 図８に示す「テストパターンの形成と計測」ＰＦＭの内容を示すフローチャートである。
【図１０】 図８に示す「パターンの検証」ＳＰＣの内容の一部を示すフローチャートである。
【図１１】 図８に示す「パターンの検証」ＳＰＣの内容の残部を示すフローチャートである。
【図１２】 図２に示す転写ベルト１０に形成されるカラーマークの分布を示す平面図、および、光センサ２０ｒの、カラーマークを読取った検出信号Ｓｄｒのレベル変化を示すタイムチャートである。
【図１３】 （ａ）は、図１２に示す検出信号Ｓｄｒのタイムチャートの一部を拡大して示すタイムチャート、（ｂ）は、（ａ）に示す検出信号の内、そのＡ／Ｄ変換データが図６に示すＭＰＵ４１の内部のＦＩＦＯメモリに書込まれる範囲のみを摘出して示すタイムチャートである。
【図１４】 図８に示す「平均パターンの算出」ＭＰＡによって算出される平均値データＭａｒ，・・・と、それらが中心点位置となる仮想マークＭＡｋｒ，・・・、すなわち平均値データ群で表されるマーク列、を示す平面図である。
【図１５】 本発明の第２実施例においてＭＰＵ４１が実行する「色合わせ」ＣＰＡの概要を示すフローチャートである。
【図１６】 本発明の第２実施例においてＭＰＵ４１が実行する「パターンの検証」ＳＰＣの内容の一部を示すフローチャートである。
【図１７】 本発明の第２実施例において転写ベルト１０に第２態様で形成するマークの分布を示す拡大平面図である。
【符号の説明】
５：書込みユニット ６ａ〜６ｄ：感光体ドラム
７ａ〜７ｄ：現像器 ８：給紙カセット
９：駆動ローラ １０：転写ベルト
１１ａ〜１１ｄ：転写器 １２：定着装置
１３ａ：テンションローラ
１３ｂ：従動ローラ ２０ｒ，２０ｆ，２０ｃ：光センサ
４１：ＭＰＵ（マイクロコンピュータ）
４００：自動原稿供給装置
ＰＣ：パーソナルコンピュータ
３１１：読取りユニット ＳＢＵ：センサボードユニット[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a color image forming apparatus that forms a color image of each color on a photoreceptor and transfers the image onto a transfer sheet, and more particularly to a color image forming apparatus having a color matching function for preventing color misregistration.
[0002]
In one embodiment of this type of color matching, a mark pattern consisting of an array of a plurality of marks arranged in the moving direction is formed on a photosensitive member, a transfer drum, or a transfer belt, and each position is detected to detect the difference between colors. There is a method of calculating an image forming position shift and finely adjusting each color image forming position so as to eliminate this.
[0003]
[Prior art]
[Patent Document 1]
Japanese Patent Laid-Open No. 11-231586 forms not only a mark pattern on a transfer belt but also a parallel line pattern for timing detection, detects a mark pattern, calculates a color shift amount, and also detects a parallel line pattern. An image forming apparatus that calculates the speed fluctuation of the transfer belt and corrects the color misregistration amount in correspondence with the speed fluctuation is disclosed.
[0004]
[Patent Document 2]
The color matching of the color image forming apparatus disclosed in Japanese Patent Application Laid-Open No. 2002-174936 filed by the inventor of the present application is carried out by supporting the transfer paper and transporting it along the arrangement of the respective color photosensitive drums, and the toner on the respective color photosensitive drums. Each color toner mark is formed in a predetermined arrangement pattern near the both ends of the width on the transfer belt for transferring the image onto the transfer paper, and the toner mark at each end is read by each of a pair of photosensors. Based on the signal, the position of each mark in the mark array (pattern) is calculated. The shift amount dy of each color image from the reference position in the sub-scanning direction y (transfer belt moving direction), the shift amount dx in the main scanning direction x (transfer belt width direction), and the effective line length of the main scanning line The shift amount dLx and the main scanning line skew dSq are calculated, and fine adjustment corresponding to the shift amount is added to the image forming timing. In reading each color toner mark, the A / D conversion data of the read signal within the range of 2 to 3 V of the read signal level of 0 to 5 V is temporarily stored in the memory, and then the center position of each mark is calculated. This color matching is automatically executed immediately after the power is turned on, after the change in the internal temperature exceeds the set value, and after the number of times of color image formation exceeds the set value. Further, it is executed in response to the replacement of the image forming unit, and is also executed when a color matching instruction is given from the user.
[0005]
[Patent Document 3]
In the color matching control disclosed in Japanese Patent Application Laid-Open No. 2003-98793 filed earlier by the inventor of the present application, in addition to a pair of optical sensors for detecting each color toner mark formed near each of the width ends on the transfer belt, Toner mark information at a position corresponding to the connection mark position detected by the third optical sensor from the toner mark detection information. Remove. This eliminates erroneous detection of toner marks due to linear scratches or dirt that crosses the belt in the width direction, not limited to connection marks.
[0006]
[Problems to be solved by the invention]
In the conventional transfer belt, when the sensor output voltage is used in the means for detecting the color matching pattern imaged on the belt by the reflection / transmission method, it is difficult to distinguish the pattern from the seam (connection) The condition was that there was no trace. This is because if there is a connection mark, the position is regarded as a color matching pattern, and as a result, the color matching adjustment data becomes inaccurate. On the other hand, a seamless endless belt that requires a dimensional accuracy such as a circumferential length in the rotation direction in manufacturing the belt is costly in manufacturing the belt.
[0007]
Therefore, the color matching control described in Patent Document 3 that realizes the use of the connection mark on the transfer belt even if it is on the transfer belt is useful. However, if the belt is worn and deteriorated over time, such as scratches and dirt, and the frequency of detecting them as connection traces increases, the number of detected marks decreases and the amount of image formation deviation with high reliability is reduced. It becomes difficult to obtain. If the number of marks detected as genuine is less than the set value, the color matching operation may be restarted from the mark formation again. However, since a long time is required for one color matching, for example, Japanese Patent Laid-Open No. 2002-174936 As in the case of the color image forming apparatus described above, when there are many opportunities for automatic color matching, if the transfer belt is worn out or deteriorated, the number of repeated color matching (mark formation again) increases. It is conceivable that the user is kept waiting. Even if the color image quality is a little low, there is a case where it is desired to execute color imaging promptly anyway.
[0008]
An object of the present invention is to reduce time during which a color image forming apparatus cannot be used by color matching for eliminating color misregistration in color image formation.
[0009]
[Means for Solving the Problems]
(1) Marks of each color (Akr, Ayr, Acr, Amr,... / Akf, Ayf, Acf, Amf,...) Are arranged in a predetermined order in the standard area on the moving surface in the moving direction (y). Mark forming means (41) formed at a distance; Mark sensor (20r / 20f) for detecting a mark of each color formed in the standard area; A predetermined monitoring area defined outside the standard area on the moving surface Monitoring sensor (20c) for detecting the image of the mark; the mark at the position corresponding to the position in the moving direction (y) of the image detected by the monitoring sensor (20c) is removed from the mark detection information of the mark sensor (20r / 20f) Color matching means (41) for adjusting the timing of each color image formation so as to eliminate the image formation deviation (dyy, dxy, dLxy /...) Between the colors based on the obtained information; Control means (41) is provided that starts color matching up to the adjustment of image formation timing in response to an execution instruction input and automatically starts when a predetermined condition is satisfied. Color image forming apparatus
The control means (41), when the number of images detected by the monitoring sensor (20c) is equal to or greater than a set value (a), restricts the subsequent automatic start of color matching, characterized in that .
[0010]
In addition, in order to make an understanding easy, the code | symbol of the corresponding element or the corresponding matter of the Example shown in drawing and mentioned later in parentheses was attached for reference as an example.
[0011]
According to this, since color matching is automatically executed not only when an instruction is input but also when a predetermined condition is satisfied, a color image without color misregistration can be formed stably. For example, when the mark detection accuracy is lowered due to deterioration of the mark forming surface, automatic activation of color matching is limited, so that the time during which the color image forming apparatus cannot be used, that is, the downtime is prevented from being extended by executing color matching.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
(2) Each color mark (Akr, Ayr, Acr, Amr,... / Akf, Ayf, Acf, Amf,...) Is arranged in a predetermined order in the standard area on the moving surface in the moving direction (y). Mark forming means (41) formed at a distance; Mark sensor (20r / 20f) for detecting a mark of each color formed in the standard area; A predetermined monitoring area defined outside the standard area on the moving surface Monitoring sensor (20c) for detecting the image of the mark; the mark at the position corresponding to the position in the moving direction (y) of the image detected by the monitoring sensor (20c) is removed from the mark detection information of the mark sensor (20r / 20f) Color matching means (41) for adjusting the timing of each color image formation so as to eliminate the image formation deviation (dyy, dxy, dLxy /...) Between the colors based on the obtained information; Control means (41) is provided that starts color matching up to the adjustment of image formation timing in response to an execution instruction input and automatically starts when a predetermined condition is satisfied. Color image forming apparatus
The control means (41) sets the number of remaining marks removed based on the position in the moving direction (y) of the image detected by the monitoring sensor (20c) from the mark detection information of the mark sensor (20r / 20f). A color image forming apparatus characterized by restricting the subsequent automatic start of color matching when out of range.
[0013]
According to this, since color matching is automatically executed not only when an instruction is input but also when a predetermined condition is satisfied, a color image without color misregistration can be formed stably. For example, when the mark detection accuracy is lowered due to deterioration of the mark forming surface, automatic activation of color matching is limited, so that the time during which the color image forming apparatus cannot be used, that is, the downtime is prevented from being extended by executing color matching.
[0014]
(3) The standard area is each end area (r, f) of the image exposure line in the direction (x) orthogonal to the moving direction (y) of the moving surface, and the monitoring area is centered on the intermediate point of the image exposure line The central region (c); the mark sensor (20r / 20f) is a pair for detecting the mark in each end region (r, f); the monitoring sensor is one for detecting the central image; The color image forming apparatus according to 1) or (2). According to this, since two sets of mark groups are formed at the longest distance in the direction (x) orthogonal to the moving direction (y), each color image plane is determined by the relative positional relationship between the corresponding marks of different sets. It is possible to precisely calculate the positional deviation between them, and to increase the color matching accuracy.
[0015]
(4) When the number of marks to be referred to for calculation of the color misregistration (dyy, dxy, dLxy /...) Between colors is insufficient, the control means (41) performs each end by the mark forming means (41). Marks of respective colors (FIG. 17) are formed in a predetermined order at predetermined distances in the region (r, f) and the central region (c); each end region (r) is formed by a mark sensor (20r / 20f) and a monitoring sensor (20c) , f) and the mark formed in the central area (c); by the color matching means (41), the mark detection in one end area (r / f) and the central area (c) where the number of detected marks is sufficient The color image forming apparatus according to (3), wherein the color image formation timing is adjusted based on the information so as to eliminate the image formation deviation (dyy, dxy, dLxy /...) Between the colors;
[0016]
According to this, when one set of detection information of the mark group (two sets) in both end regions (r, f) is insufficient, an image is formed between colors using the mark detection information in the central region (c) instead. Each color image forming timing can be adjusted so as to eliminate the shift (dyy, dxy, dLxy /...). For example, even when the mark detection accuracy is lowered due to deterioration of the mark forming surface, there is a high possibility that color matching can be completed, and long-term stabilization of image quality can be achieved.
[0017]
(5) The control means (41) generates automatic start prohibition information (FAP = 1) when the condition for restricting the automatic start is satisfied, and the control means (41) prohibits the automatic start. The color image forming apparatus according to any one of (1) to (4), wherein when there is information, automatic activation is suspended.
[0018]
For example, in a mode in which automatic start prohibition information (FAP = 1) is deleted (initialized to FAP = 0) immediately after the device is turned on and color matching is automatically started, color matching is surely automatically started immediately after the device is turned on. However, if the automatic start prohibition information (FAP = 1) occurs while the power is on, the number of color images formed will remain at the set value until the power is turned off. Even if it exceeds, color matching is not automatically started. The color matching is started when the user inputs a color matching execution instruction, or when the power is turned off and the power is turned on again. In an embodiment described later, when automatic start prohibition information (FAP = 1) occurs, a warning related to color matching failure is displayed on the operation board.
[0019]
(6) The control means (41) is at least immediately after the color image forming apparatus is turned on, after the number of color image forming sheets exceeds a set value, and after the in-machine temperature of the color image forming apparatus changes by more than a set value. The color image forming apparatus according to (5), wherein the color matching is started on the condition that one is established and there is no automatic start prohibition information (FAP = 0).
[0020]
According to this, when the accuracy of mark formation and detection is high, color matching is performed efficiently and frequently, and the image quality is always high. When the accuracy of mark formation or detection is reduced, the frequency of color matching is reduced, and prolonged downtime due to color matching is avoided.
[0021]
(7) The control means (41) activates the color matching in response to an execution instruction input even if the automatic activation prohibition information (FAP = 1) is present, according to (5) or (6) above Color image forming apparatus.
[0022]
(8) The control means (41) activates the color matching when the image forming unit is replaced even if the automatic activation prohibition information (FAP = 1) is present. (5), (6 Or a color image forming apparatus according to (7).
[0023]
Other objects and features of the present invention will become apparent from the following description of embodiments with reference to the drawings.
[0024]
【Example】
-1st Example-
FIG. 1 shows the appearance of a multi-function full-color digital copying machine according to an embodiment of the present invention. This full-color copying machine is roughly constituted by units of an automatic document feeder (ADF) 400, an operation board 610, a color scanner 300, a color printer 100, and a paper feed table 200. A LAN (Local Area Network) connected to a personal computer PC is connected to the system controller 630 (FIG. 2) in the apparatus. The system controller 630 (FIG. 2) of the copying machine can be connected to a communication network (Internet), and can exchange data by communicating with a management server of a management center (not shown) via the communication network. . Further, the facsimile controller FCU (FIG. 2) in the machine can perform facsimile communication via the exchange PBX and the public communication network PN.
[0025]
FIG. 2 shows a system configuration of image reading, image processing, image storage and image formation of the copying machine shown in FIG. A reading unit 311 that optically reads a document of the color document scanner 300 scans a document with a document illumination light source, and forms a document image on a CCD of an SBU (sensor board unit). The original image, that is, the reflected light of light irradiation on the original is photoelectrically converted by the CCD to generate R, G, B image signals, converted to RGB image data on the SBU, shading corrected, and output I / F (interface) In 312, the image data is sent to an image data processor IPP (Image Processing Processor; hereinafter simply referred to as IPP) via an image data bus.
[0026]
The IPP performs separation generation (determination of whether an image is a character area or a photographic area: image area separation), background removal, scanner gamma conversion, filter, color correction, scaling, image processing, printer gamma conversion, and gradation processing. IPP is a programmable arithmetic processing means for performing image processing. Image data transferred from the scanner 300 to the IPP is corrected for signal deterioration (scanner signal deterioration) due to quantization into an optical system and a digital signal by the IPP, and is written in the frame memory 601.
[0027]
The system controller 630 has functions of a plurality of applications such as a scanner application, a facsimile application, a printer application, and a copy application, and controls the entire system. The operation panel control device 631 is a device that decodes the input of the operation board 610 and displays the settings of the system and the state contents thereof. The image data bus / control command bus is a bus through which image data and control commands are transferred in a time division manner.
[0028]
The CPU 605 of the system controller 630 controls the system controller 630. In the ROM 604, a control program for the system controller 630 is written. A RAM 603 is a working memory used by the CPU 605. The NVRAM 602 is a nonvolatile memory and stores information on the entire system.
[0029]
The external device communication control 606 controls communication with an external device (for example, the same type of copying machine, image scanner, personal computer, printer, facsimile) requesting image reading, image storage or image printing, and a management server of the management center. Yes, it controls the physical I / F for connecting to the network. When the external device communication control 606 connected to the network receives data from the network, only the content of the communication data is sent to the system I / F 607 from an electrical signal. In the system I / F 607, the received data is logically converted in accordance with a prescribed protocol and sent to the CPU 605. The CPU 605 determines and processes the logically converted received data. When the CPU 605 transmits data to the network, the transmission data is transmitted to the system I / F 607 and the external device communication control 606 in the reverse order of reception, and is transmitted as an electric signal on the network.
[0030]
The system I / F 607 controls the transfer of document reading data, facsimile reception data, personal computer document data (printing commands), and image data for printing personal computer document data, which are processed in the system according to a command from the CPU 605. Image data) and transfer. The work memory 600 is a working memory for image development (conversion from document data to image data) used in the printer. The frame memory 601 is a working memory that temporarily stores image data of a read image and a written image that are printed immediately while power is continuously supplied.
[0031]
The HDDC 650 is used as an application database that stores system application programs and device activation information of image forming process devices of the printer 100, and an image database that stores image data of read images and written images, that is, image data and document data. Hard disk HDD and its controller. Image data and document data may be encoded or dot images. The FIFO buffer memory 609 performs data transfer rate conversion when writing an input image to the frame memory 601. In other words, temporary storage of data that absorbs the difference between the data transmission / reception timing of the transfer source and the transfer destination, the difference in the data amount of the transfer unit, the transfer speed difference, etc. Data is sent out at the transfer timing and speed of the transfer destination. Similarly, the FIFO buffer memory 608 performs speed conversion when transferring the image data of the frame memory 601 as an output image.
[0032]
The memory controller 610 controls input / output of images between the frame memory 601 and the HDDC 650 and the bus without the control of the CPU 605. In addition, according to a command received by the input device 614 of the operation board 301, the frame memory 601 is used to edit, process, or combine images stored in the HDDC. The memory controller 610 reads image information from the HDD of the HDDC 650 to the work memory 600 or the frame memory 601 and changes the image printing direction on the transfer paper, image rotation, image combination editing mainly by the image data address changing operation. Various kinds of images by density conversion by addition / subtraction / division / division of image data, image trimming and synthesis by logical product operation or logical sum operation of image data, and writing of image information processed in this way to the HDD. Processing and editing can be performed.
[0033]
The CPU 617 performs input / output control of the operation board 610. That is, input reading and display output of the operation board 610 are controlled. In the ROM 616, a control program for the operation board 610 is written. A RAM 618 is a working memory used by the CPU 617. Reference numeral 614 denotes an input device in which the user inputs system settings by operating the input keys and the input panel of the operation board 610. The display device 615 is provided on the operation board 610 and displays the setting contents and state of the system to the user, and includes a display panel (liquid crystal touch panel) having an indicator lamp and an input function.
[0034]
FIG. 3 shows the image forming unit PTR of the color printer 100. The image forming unit PTR is a tandem type color image forming mechanism. The image data of each color generated by the scanner 300 (FIG. 2) is IPP (FIG. 2) for color recording of Bk (black), Y (yellow), C (cyan), and M (magenta). After being converted into image data (hereinafter, recorded image data or simply image data), each is sent to a writing unit (exposure device) 5 of the printer PTR. The writing unit 5 is a laser that is modulated with image data for M, C, Y, and Bk recording on each of the photosensitive drums 6a, 6b, 6c, and 6d for M, C, Y, and Bk recording in accordance with the recorded image data. The light beam is scanned and projected to form an electrostatic latent image. Each electrostatic latent image is developed with each of the M, C, Y, and Bk toners by the developing devices 7a, 7b, 7c, and 7d to form toner images (visual images) of the respective colors.
[0035]
On the other hand, the transfer paper is conveyed from the paper feed tray of the paper feed cassette 8 or the paper feed bank 200 (FIG. 1) onto the transfer belt 10 of the transfer belt unit, and each color image (development) developed and formed on each photosensitive drum. Image) are sequentially transferred onto the transfer paper by the transfer devices 11a, 11b, 11c and 11d, and after being superimposed, they are fixed by the fixing device 12. After the fixing, the transfer paper is discharged out of the machine.
[0036]
The transfer belt 10 is a translucent endless belt supported by a drive roller 9, a tension roller 13a, and a driven roller 13b, and the tension roller 13a pushes down the belt 10 with a spring (not shown). The tension of the belt 10 is substantially constant.
[0037]
In order to prevent the above-described color shift of the superposition transfer, the printer PTR uses the exposure device 5 to bring the photosensitive drums 6a, 6b, 6c and 6d to the front (front side in FIG. 3; hereinafter referred to as front (f)). (Representation) and back (back side in FIG. 3; hereinafter referred to as rear (r)), a test pattern (FIG. 5) for position detection is written and developed, transferred onto the transfer belt 10, and transferred to the transfer belt 10. By reading the test pattern with the reflection type optical sensors 20f (front side) and 20r (rear side) facing the back reflector 21 which supports the transfer belt on the back surface, the photosensitive drums 6a, 6b, 6c and 6d are read. The writing position deviation, inclination, magnification, and the like of the exposure apparatus 5 with respect to the photosensitive drum are detected, and the writing timing of the exposure apparatus 5 on each photosensitive drum is set so as to eliminate the color deviation caused by these. It is configured so as positively to. A similar reflection type optical sensor 20c is similarly arranged at an intermediate point between the reflection type optical sensors 20f and 20r.
[0038]
FIG. 4 shows the arrangement positions of the optical sensors 20r, 20c, and 20f with respect to the transfer belt 10. In FIG. 4, the transfer belt 10 rotates counterclockwise by a loop supported by the rollers 9, 13 a, and 13 b, but the detection visual field center lines of the optical sensors 20 r, 20 c, and 20 f are on the surface of the transfer belt 10. It is perpendicular and crosses the surface of the transfer belt 10 at the same position (same width line) in the y direction along the loop.
[0039]
In the process controller 131 (FIG. 2), an electric circuit (driver) and a detection device for driving an electric device and an electric sensor such as a motor, a solenoid, a charger, a heater, and a lamp incorporated in the printing mechanism of the printer PTR, that is, the image forming mechanism. There is a mechanism drive electric system including a circuit (signal processing circuit), the operation of these electric circuits is controlled by an MPU 41 (FIG. 6) described later in the process controller 131, and the detection signal (operation state) of the electric sensor is MPU 41. Is read in.
[0040]
As shown in FIG. 5, a test pattern is formed on the transfer belt 10 of the printer PTR when “color matching” is performed. In other words, eight mark sets are sequentially formed at the set pitch (constant pitch) 7d + A + c after the vacant space of 4 pitches 4d of the mark pitch d, starting with the black Bk start mark Msr.
[0041]
The first mark set is a next orthogonal mark group parallel to the main scanning direction x (the width direction of the transfer belt 10),
Black Bk first orthogonal mark Akr,
Yellow Y second orthogonal mark Ayr,
A cyan C third orthogonal mark Acr, and
Magenta M 4th orthogonal mark Amr,
And the following oblique mark group forming an angle of 45 ° with respect to the main scanning direction x,
Bk's first oblique mark Bkr,
Y second oblique mark Byr,
C third oblique mark Bcr, and
M's fourth oblique mark Bmr,
Is included. The contents of the second to eighth mark sets are the same as the first mark set. The same test pattern as the above-described rear test pattern is also formed on the front at the same time. Of the symbols attached to the marks included in these test patterns, the suffix r indicates the rear side, and f indicates the front side.
[0042]
FIG. 6 shows optical sensors 20r, 20c, and 20f and circuits 30r, 30c, and 30f that process their detection signals. At the mark detection stage, a microcomputer (hereinafter referred to as MPU) 41 (mainly referred to as MPU) including a ROM, RAM, CPU and a FIFO memory for storing detection data is connected to the D / A converters 37r, 37c, and 37f as optical sensors. The energization data designating energization current values of the light emitting diodes (LEDs) 31r, 31c, and 31f of 20r, 20c, and 20f is given, and the D / A converters 37r, 37c, and 37f convert the analog data into the analog voltage, and the LED drivers 32r, 32c and 32f. These drivers 32r, 32c, and 32f energize the LEDs 31r, 31c, and 31f with a current proportional to the analog voltage.
[0043]
The light generated by the LEDs 31r, 31c, and 31f passes through the slit (not shown) and strikes the transfer belt 10, and most of the light is transmitted therethrough to slidably contact the back surface of the transfer belt 10 to suppress vertical vibration of the belt 10. The light is reflected by the back reflector 21, passes through the transfer belt 10, and further strikes the phototransistors 33 r and 33 f through a slit (not shown). As a result, the impedance between the collector and emitter of the transistors 33r and 33f becomes low, and the emitter potential rises. When the aforementioned mark Msr or the like arrives at a position opposite to the LEDs 31r and 31f, the mark blocks light, so that the collector / emitter between the transistors 33r and 33f becomes high impedance, and the emitter voltage, that is, the photosensors 20r and 20f. The level of the detection signal decreases. Therefore, as described above, when the test pattern is formed on the moving transfer belt 10, the detection signals of the optical sensors 20r and 20f fluctuate between high and low. A high voltage means no mark, and a low voltage means a mark.
[0044]
In this embodiment, no mark is formed at the position facing the optical sensor 20c. The optical sensor 20c detects connection marks (seam marks), scratches and dirt on the transfer belt 10 which is an endless belt (loop) by connecting both ends of the belt-like body. Since the connection trace extends over the entire belt width, if the optical sensors 20r and 20f detect it as a registration mark, the calculation of the amount of color misregistration based on the mark detection signals of the optical sensors 20r and 20f may cause an error. . In this embodiment, as will be described in detail later, the mark detection signals of the optical sensors 20r and 20f at the positions where the optical sensor 20c detects that there is a connection trace are invalidated.
[0045]
The detection signals of the optical sensors 20r, 20c, and 20f are further calibrated to 0 to 5V by the level calibration amplifiers 35r, 35c, and 35f through the low-pass filters 34r, 34c, and 34f for removing high-frequency noise. It is applied to the A / D converters 36r, 36c, 36f.
[0046]
FIG. 12 shows the calibrated detection signal Sdr. Referring again to FIG. 6, the detection signals Sdr and Sdf are supplied to the A / D converters 36r and 36f, and further supplied to the window comparators 39r and 39f through the amplifiers 38r and 38f.
[0047]
The A / D converters 36r and 36f are provided with a sample hold circuit on the input side and a data latch (output latch) on the output side, and when the MPU 41 gives A / D conversion instruction signals Scr and Scf, The voltages of the detection signals Sdr and Sdf are held, converted into digital data, and held in the data latch. Therefore, when it is necessary to read the detection signals Sdr and Sdf, the MPU 41 can read the digital data representing the levels of the detection signals Sdr and Sdf by giving the instruction signals Scr and Scf, that is, the detection data Ddr and Sdf.
[0048]
The window comparators 39r and 39f generate level determination signals Swr and Swf at a low level L when the detection signals Sdr and Sdf are within a range of 2V or more and 3V or less and when they are outside the range. The MPU 41 can immediately recognize whether or not the detection signals Sdr and Sdf are within the range by referring to these level determination signals Swr and Swf.
[0049]
The contents of the detection signal processing by the circuit 30c of the optical sensor 20c and the detection signal reading process of the MPU 41 are the same as the contents of the above-described circuits 30r and 30f and the detection signal reading process of the MPU 41.
[0050]
FIG. 7 shows an outline of printer engine control, that is, print control of the MPU 41. When the operating voltage is applied to itself, the MPU 41 sets the signal level of the input / output port to the standby state, and also sets the internal registers and timers to the standby state (step 1). In the following, step No. is enclosed in parentheses. Alternatively, when indicating a step symbol, the word “step” is omitted, and the “No. Write only numbers or symbols. When the initialization (1) is completed, the MPU 41 reads the state of each part of the mechanism and the electric circuit to check whether there is an abnormality that hinders image formation (2, 3). The information is displayed on the board 610 (4), and the state reading (2) is repeated until there is no abnormality.
[0051]
In this abnormality notification 2 (4), four switches SwPi (PCU replacement switches) for detecting the mounting of the image forming units (photosensitive drum holding units) for the four colors, i = k, y, c, m, If, for example, SwPk is open (H), the electric motor of the photosensitive drum driving system is energized to check whether the switch SwPk is closed within a predetermined time.
[0052]
In addition, each image forming unit, when new, is screwed into the female screw hole of the unit case and has a small protrusion outward from the case, but when the unit is mounted on a copying machine and the photosensitive drum is driven to rotate, Since there is a male screw pin that rotates in conjunction with this and projects from the unit case to switch the switch SwPi from open to closed, and the screw connection with the female screw hole is released, the projecting member remains as described above. When the drum drive system electric motor is energized and the photosensitive drum is driven to rotate, a switch for detecting the attachment / detachment of the newly installed image forming unit, for example, SwPk is switched from open (H) to closed (L). The
[0053]
The MPU 41 monitors this switching and knows that the Bk imaging unit has been replaced. For example, when SwPk is switched from open (H) to closed (L), the cumulative number of prints addressed to the Bk imaging unit. The register (one area on the non-volatile memory) is cleared (the Bk print integration number is initialized to 0), information indicating that the switch SwPi has changed open / closed is generated, and saved in the register. This information is referred to in step 10 described later. In this case, since all the switches SwPi are closed (L), that is, become normal, the process proceeds from step 4 to 2 and then to 5 through step 3.
[0054]
It is checked whether the four switches SwPi, i = k, y, c, m are closed (L), and there is an open (H) switch, for example, SwPk, to drive the photosensitive drum. Regardless, when the switch SwPk is not switched to the closed state, it is assumed that there is no Bk image forming unit, and the abnormality notification indicating it is continued.
[0055]
If there is no abnormality, the energization of the fixing device is started, and it is checked whether the fixing temperature is the fixing possible temperature. If the fixing temperature is not, the standby display is displayed. (5).
[0056]
Also, it is checked whether the fixing temperature is 60 ° C. or higher (6). If the fixing temperature is lower than 60 ° C., the power of the copier is turned on after a long pause (not in use) (for example, the first power source in the morning) ON: The in-flight environment during suspension is greatly changed). If automatic execution of color matching is not prohibited (FAP = 0), color execution is displayed on the operation display board 610 (6a-7). In the MPU 41 register (one area of the memory) RCn, the accumulated number of color prints PCn held in the nonvolatile memory at that time is written (8), and the in-machine temperature at that time is written in the MPR 41 register RTr (9). "Color matching" (CPA) is executed. The contents of this “color matching” (CPA) will be described later with reference to FIG.
[0057]
Note that data 0 of the register FAP shown in step 6a means that color matching automatic execution is permitted, data 1 means prohibited, and when data 1 (FAP = 1), Steps 7 to 9 and “color matching” (CPA) are not executed. The data in the register FAP is initialized to 0 by initialization (1 in FIG. 7), and is changed to 1 in step 36 shown in FIG.
[0058]
Refer to FIG. 7 again. When the fixing temperature is 60 ° C. or higher, it can be considered that the elapsed time from the previous power-off of the copier is short. In this case, it can be inferred that the change in the in-flight environment immediately before the last power-off is small. However, it is checked whether the image forming unit of any color has been replaced, that is, whether or not information indicating that the switch SwPi (PCU replacement switch) has been opened / closed has been generated in Step 4 described above. (10). If the information is present, that is, if the image forming unit has been replaced, the above-described steps 7 to 9 are executed, and “color matching” (CPA) described later is executed.
[0059]
When the image forming unit has not been replaced, the MPU 41 waits for an operator input via the operation display board 610 and a command from the personal computer PC (11). Here, when a “color matching” instruction is given from the operator via the operation display board 610 (12), the MPU 41 executes the above-described steps 7 to 9, and executes “color matching” (CPA) described later. To do.
[0060]
When the fixing temperature is fixable temperature and each part is ready, if there is a copy start instruction from the operation display board 610, or if there is a print start instruction corresponding to the print command from the personal computer PC from the system controller 630 The MPU 41 forms a specified number of images (m13, m14). In this image formation, every time one sheet is formed and ejected, the MPU 41, when it is color recording, print total number register, color print integration number register PCn, and Bk allocated to the nonvolatile memory. , Y, C, and the M print accumulated number register are incremented by one. When monochrome recording is performed, the data in the total print number register, monochrome print integration number register, and Bk print integration number register are incremented by one.
[0061]
The data in the Bk, Y, C, and M print integration number registers are initialized (cleared) to data representing 0 when the Bk, Y, C, and M image forming units are replaced with new ones, respectively.
[0062]
The MPU 41 checks whether there is an abnormality such as a paper trouble every time an image is formed, and reads the development density, fixing temperature, in-machine temperature, and other statuses after completing the designated number of printouts ( 15). If there is an abnormality, it is displayed on the operation display board 610 (17), and the state reading (15) is repeated until there is no abnormality.
[0063]
When the image formation can be resumed, that is, when normal, the MPU 41 checks whether the internal temperature at that time has changed by more than 5 ° C from the internal temperature at the previous color matching (data RTr in the register RTr). (18). When there is a temperature change exceeding 5 ° C., the MPU 41 executes the above-described steps 7 to 9 and executes “color matching” (CPA) described later on condition that FAP = 0. When there is no temperature change exceeding 5 ° C, the value PCn of the color print accumulation number register PCn is 200 or more more than the value RCn (data of the register RCn) of the color print accumulation number register PCn at the previous color matching. If there are more than 200 sheets, the above steps 7 to 9 are executed, and “color matching” (CPA) described later is executed. If it is less than 200 sheets, it is checked whether or not the fixing temperature is the fixing possible temperature. If it is not the fixing possible temperature, a standby display is displayed, and if it is the fixing possible temperature, a printable display is displayed (20). Then, the process proceeds to “input reading” (11).
[0064]
According to the control flow shown in FIG. 7, the MPU 41 (1) when the power is turned on when the fixing temperature is less than 60 ° C., (2) any of the Bk, Y, C and M imaging units is new. (3) When there is a color matching instruction from the operation display board 610, (4) When the printout for the specified number of sheets is completed, FAP = 0, and the temperature inside the machine when the machine temperature is the previous color matching And when (5) the printout of the designated number of sheets is completed, FAP = 0 and the color print accumulation number PCn is 200 than the value RCn at the previous color matching. When the number increases, “color matching” (CPA) described below is executed.
[0065]
FIG. 8 shows the contents of “color matching” (CPA). When proceeding to this “color matching” (CPA), the MPU 41 first initializes the execution number n of “test pattern formation and measurement” (PFM) to 0 (31), and then “test pattern formation and measurement” ( In PFM), all image forming conditions such as charging, exposure, development and transfer are set to reference values, and start marks are respectively formed on the transfer belt 10 on the rear r and front f as shown in FIG. Msr, Msf and 8 sets of test patterns are formed, the marks are detected by the optical sensors 20r, 20f, and the mark detection signals Sdr, Sdf are converted into digital data, that is, mark detection data Ddr, Ddf by the A / D converters 36r, 36f. Convert to and read. At this time, the detection signal Sdc of the connection mark (including scratches, dirt, etc., the same applies hereinafter) is also converted by the optical sensor 20c into digital data, that is, connection mark detection data Ddc and read by the A / D converter 36c. Then, the position on the transfer belt 10 of the center point of each mark and connection mark (the midpoint of the width in the y direction) is calculated. The contents of this “test pattern formation and measurement” (PFM) will be described later with reference to FIG.
[0066]
Next, in “Pattern verification” (SPC), a connection mark having a density and a width in the y direction that may affect the detection of the registration mark based on the connection mark detection data Ddc is extracted and registered in the memory. Based on Ddr and Ddf, a mark that does not interfere with the connection mark is detected and registered, and the marks on the rear side (r) and the front side (f) are set as information on four adjacent color marks. Group into The contents of this “pattern verification” (SPC) will be described later with reference to FIGS.
[0067]
Referring to FIG. 9 again, if the detected connection mark (registered in the memory) is a (set value of 2 or more), the transfer belt 10 has many scratches and dirt (mark detection accuracy is low). Assuming that the data 1 for prohibiting automatic color matching is written into the register FAP (internal memory of the MPU 41) (32-36), information indicating the transfer belt abnormality, cleaning or replacement is required. It is displayed on 615 (37). Then, the process proceeds to the next step 33.
[0068]
In step 33, it is checked whether the number of detected mark sets is not less than b and not more than c of set values b and c (c ≧ b) of 2 or more, and if so, “calculate average pattern” (MPA) I do. If the number of mark sets is out of the range from b to c, the measurement number n is incremented by 1, and “test pattern formation and measurement” (PFM) and “pattern verification” (SPC) are performed ( 34, 35). “Test pattern formation and measurement” (PFM) and “pattern verification” (SPC) are repeated until the number of mark sets is from b to c. In the meantime, when the number of repeated executions n reaches a set value d of 2 or more, data 1 for prohibiting automatic color matching is written in the register FAP (35-36).
[0069]
When the number of mark sets is within the range of b to c, the MPU 41 performs “average pattern calculation” (MPA), and the rear side has a maximum of 8 sets of average patterns (an average value group of mark positions); A maximum of 8 sets of average patterns are calculated on the same front side.
[0070]
When the average pattern is calculated, an image shift amount by each of the Bk, Y, C, and M image forming units is calculated based on the average pattern (DAC), and an adjustment for eliminating the shift based on the calculated shift amount. (DAD).
[0071]
FIG. 9 shows the contents of “test pattern formation and measurement” (PFM). As shown in FIG. 5, the MPU 41 proceeds to the surface of the rear side r and the front side f of the transfer belt 10 that is driven at a constant speed of, for example, 125 mm / sec. Formation of start marks Msr, Msf and 8 sets of test patterns with w of 1 mm, length A in the x direction of 20 mm, pitch d of 6 mm, and set interval c of 9 mm, for example, was started. The count-up of a belt synchronization pulse (belt pulse) that generates one pulse per movement of a predetermined minute distance is started (41). When the test pattern formation is completed, the belt pulse count value Tw1 at that time is saved in a register (memory) (42, 43).
[0072]
As already described, when the Bk, Y, C, or M mark is not present in the field of view of the optical sensors 20r and 20f, the detection signals Sdr and Sdf of the optical sensors 20r and 20f are at the high level H (5V) and the mark is present. The detection signal Sdr is at a low level L (0 V), and the detection signal Sdr varies as shown in FIG. A part of the fluctuation is enlarged and shown in FIG. In this case, the descending area where the level of the mark detection signal is reduced corresponds to the leading edge area of the mark, and the ascending area where the mark is rising corresponds to the trailing edge area of the mark. Between these is the area of the mark width w.
[0073]
Refer to FIG. 9 again. The MPU 41 detects that the window comparator 39c in FIG. 6 indicates that the detection signal Sdc is at 2 to 3V in the process in which the connection mark arrives in the field of view of the optical sensor 20c and the detection signal Sdc changes from H to L. Wait until signal Swc = L (45). Further, in the process in which the start marks Msr and Msf arrive at the field of view of the optical sensors 20r and 20f and the detection signals Sdr and Sdf change from H to L, the window comparator 39r or 39f in FIG. 6 detects the detection signal Sdr or Sdf. , And wait until the detection signal Swr = L or Swf = L indicating that the voltage is 2 to 3 V (49). That is, it is monitored whether at least one edge region of the start marks Msr and Msf has arrived in the visual field of the optical sensors 20r and 20f (49).
[0074]
When a connection trace arrives at the optical sensor 20c, 1 representing it is written to the register FSwc, a timer Tspc with a time limit value of Tsp (for example, 50 μsec) is started, and when it expires, “timer Tspc interrupt” (TIPc The timer interrupt is permitted (45 to 47). Then, the sampling number value Nosc of the sampling number register Nosc is initialized, and the write address Noac of the c memory (connection trace read data storage area) allocated to the FIFO memory in the MPU 41 is initialized to the start address (48).
[0075]
When the start mark Msr, Msf arrives in one of the optical sensors 20r, 20f, 1 representing the start mark is written in the register FSwrf, and the timer Tsp whose time limit value is Tsp (for example, 50 μsec) is started. Then, “timer Tsp interrupt” (TIP) is executed, and timer interrupt is permitted (49-51). Then, the sampling number value Nos of the sampling number register Nos is initialized to 0, and writing to the r memory (rear side mark reading data storage area) and the f memory (front side mark reading data storage area) allocated to the FIFO memory in the MPU 41 is performed. Addresses Noar and Noaf are initialized to start addresses (52). Then, it waits for the count value of the belt pulse to reach a timing value at which all of the eight sets of test patterns pass through the visual fields of the optical sensors 20r and 20f (53).
[0076]
Here, the contents of the “timer Tsp interrupt” (TIP) will be described. It should be noted that this process is executed every time the timer Tsp whose time limit value is Tsp expires. At the beginning of this process, the MPU 41 restarts the timer Tsp and instructs the A / D converters 36r and 36f to perform A / D conversion. That is, the instruction signals Scr and Scf are temporarily set to the A / D conversion instruction level L. Then, the sampling number value Nos of the sampling number register Nos, which is the number of instructions, is incremented by one. Thereby, the Nos × Tsp has elapsed since the detection of the leading edge of the start mark Msr or Msf (= light in the belt moving direction y along the surface of the transfer belt 10 based on the start mark Msr or Msf. This represents the current detection position on the transfer belt 10 by the sensors 20r and 20f.
[0077]
Then, it is checked whether the detection signal Swr of the window comparator 39r is L (the optical sensor 20r is detecting the edge portion of the mark and 2V ≦ Sdr ≦ 3V), and if so, the address Noar of the r memory is set. As the write data, the sampling number value Nos of the sampling number register Nos, the count value of the belt pulse and the A / D conversion data Ddr (value of the mark detection signal Sdr of the optical sensor 20r) are written. Then, the write address Noar of the r memory is incremented by one. When the detection signal Swr of the window comparators 39r and 39f is H (Sdr <2V or 3V <Sdr), data is not written to the r memory. This is for reducing the amount of data written to the memory and simplifying subsequent data processing.
[0078]
Next, similarly, it is checked whether the detection signal Swf of the window comparator 39f is L (the optical sensor 20f is detecting the edge portion of the mark, and 2V ≦ Sdf ≦ 3V). At address Noaf, the sampling number value Nos of the sampling number register Nos, the belt pulse count value, and the A / D conversion data Ddf (value of the mark detection signal Sdf of the optical sensor 20f) are written as write data. Then, the write address Noaf of the f memory is incremented by one.
[0079]
Since such interrupt processing is repeatedly executed at the Tsp cycle, when the mark detection signals Sdr and Sdf of the optical sensors 20r and 20f change to high and low as shown in FIG. 13A, the FIFO in the MPU 41 In the r memory and the f memory allocated to the memory, only the digital data Ddr and Ddf of the detection signals Sdr and Sdf within the range of 2V to 3V shown in FIG. It is stored together with the pulse count value. The belt pulse count value indicates the y position from the count start position along the surface of the transfer belt 10.
[0080]
The content of the “timer Tspc interrupt” (TIPc) is the same as the above “timer Tsp interrupt” (TIP). However, here, the mark detection signal is read as a connection mark detection signal.
[0081]
In addition, as shown in FIG. 13B, the center position a of the descending area where the level of the mark detection signal is lowered and the center position of the ascending area that is rising next is within the range of 2V to 3V. The middle point Akrp of b is the center position of one mark Akr in the y direction, and similarly, the center position c of the descending region where the level of the mark detection signal that appears next to the mark is lowered, and the next rise The middle point Ayrp of the center position d of the rising area is the center position in the y direction of another mark Ayr. These mark center positions Akrp, Ayrp,... Are calculated in the mark center point position calculation CPA (FIG. 9), which will be described later, and the connection mark center position is calculated.
[0082]
Reference is again made to FIG. After the last mark of the last eighth set in the test pattern passes through the optical sensors 20r and 20f, the MPU 41 prohibits interruption of the timers Tspc and Tsp (53, 54). As a result, the A / D conversion of the detection signals Sdc, Sdr, Sdf in the Tspc, Tsp cycle is stopped. The MPU 41 calculates the connection mark and the center position of the mark based on the detection data Ddc, Ddr, and Ddf in the c memory, the r memory, and the f memory of the FIFO memory (CPA).
[0083]
In the “calculation of mark center point position of rear r” (CPAr), the MPU 41 first initializes the read address RNoar of the r memory allocated to the FIFO memory inside thereof, and the data of the center point number register Noc is transferred to the first edge. Is initialized to 1 which means Then, the data Ct in the one-edge region sample number register Ct is initialized to 1, and the data Cd and Cu in the descending number register Cd and the ascending number register Cu are initialized to 0. Then, the read address RNoar is written into the edge area data group start address register Sad. The above is preparation processing for data processing of the first edge region. Next, the MPU 41 receives data (y position (belt pulse count value), detection level Ddr: D · RNoar) from the address RNoar in the r memory, and data (y position, detection level Ddr: from the next address RNoar + 1). D · (RNoar + 1)) is read, and first, it is checked whether the y position difference between the two data is E (for example, E = w / 2 = for example, a value equivalent to 1/2 mm) or less (on the same edge region). If the mark detection data Ddr has a downward trend or an upward trend, the data Cd in the downward count register Cd is incremented by 1 if it is downward, and the data Cu of the upward count register Cu indicates that the mark detection data Ddr is upward. 1 increment. Then, the data Ct in the one-edge sample number register Ct is incremented by one. Then, it is checked whether the r memory read address RNoar is the end address of the r memory. If the r memory read address RNoar is not the end address, the memory read address RNoar is incremented by 1 and the above processing is repeated.
[0084]
When the MPU 41 finishes checking all of the sampling data in one mark edge (leading edge or trailing edge), the sample number data Ct in the one-edge sample number register Ct is It is checked whether the value is equivalent to one edge region (within a range of 2V to 3V). That is, it is checked whether F ≦ Ct ≦ G. F is a lower limit (setting of the number of times of writing the sample value Ddr to the r memory while the detection signal Sdr is 2 V or more and 3 V or less when the leading edge or the trailing edge of the mark formed normally is detected. Value) and G are upper limit values (set values).
[0085]
If Ct is F ≦ Ct ≦ G, the correctness / incorrectness of the data of one mark edge that has been normally read and stored is completed, and the result is “appropriate”. It is checked whether the obtained detection data group has a downward trend or an upward trend as a whole of the edge region (2 V or more and 3 V or less). In this embodiment, if the data Cd of the descending number register Cd is 70% or more of the sum Cd + Cu of the data Cu of the descending number register Cu and the data Cu of the ascending number register Cu, the memory edge No. When the information Down indicating the descending is written to the address addressed to Noc, and the data Cu in the ascending number register Cu is 70% or more of Cd + Cu, the memory edge No. Information Up indicating an increase is written in the address addressed to Noc. Further, the average value of the y position data of the edge region, that is, the center point position of the edge region (a, b, c, d,... Write to the address addressed to Noc. Next, the edge No. It is checked whether Nos has become 130 or more, that is, calculation of the center positions of the leading edge region and trailing edge region of all of the start mark Msr and the eight sets of mark patterns has been completed. If this is completed, or if all the stored data has been read from the r memory, the mark center point position is calculated based on the edge center point position data (calculated y position). That is, the memory edge No. The address data (falling / rising data & edge center point position data) is read, and the position difference between the center point position of the preceding falling edge area and the center point position of the immediately following rising edge area is the width in the y direction It is checked whether it is within the range corresponding to w. If it is out of range, these data are deleted. If it is within the range, the average value of these data is set as the center point position of one mark. Write to memory. If mark formation, mark detection, and detection data processing are all appropriate, with respect to rear r, start mark Msr and 8 sets of marks (1 set 8 marks × 8 sets = 64 marks), a total of 65 mark center points Position data is obtained and stored in memory.
[0086]
Next, the MPU 41 executes “calculation of the position of the mark center point of the front f” and performs the data processing of “calculation of the position of the mark center point of the rear r” similarly to the measurement data on the f memory. . With respect to the front f, if mark formation, measurement, and measurement data processing are all appropriate, start mark Msf and 8 sets of marks (64 marks), a total of 65 mark center point position data are obtained and stored in memory. Is done. Further, the MPU 41, like the data processing of “calculation of the mark center point position of the rear r” described above (however, there is no check of the y-direction width w), the “measurement point center point position of the connection trace” "Calculation of".
[0087]
FIG. 10 shows the contents of “pattern verification” (SPC in FIG. 8) to be executed after “calculation of mark center point position” (CPA) described above. Here, the MPU 41 firstly performs “validation of connection trace” (60), and determines the y width of each connection trace having a center position calculation value (the end point y position of the section where the detection signal is 3V or less in FIG. 13A). (Start point y position) is calculated (61, 62), and a connection trace whose y width is equal to or larger than the set value e is stored in the c memory with the y region from the start point y position -f to the end point + f (f is a set value). Register (63-65).
[0088]
Next, the MPU 41, in “ver mark verification” (70), the y width of each mark having a center position calculated value (the end point y position-start point y of the section where the detection signal is 3V or less in FIG. 13A). (Position) is calculated (71, 72), and it is checked whether this y width (y position at the start point or end point) interferes with (enters) the y area of the connection trace registered in the c memory. And checks whether the y width of the mark that does not interfere is within the set width range (73, 74), and registers the center position of only the mark within the set width range in the r memory addressed to the mark (75). .
[0089]
Next, referring to FIG. 11, the MPU 41 calculates the y width of each mark having a center position calculation value (81, 82) in the “verification of f mark” (80), and this y width is stored in the c memory. It is checked whether or not it interferes with the y region of the registered connection trace, the interfering mark is excluded, and it is checked whether the y width of the mark that does not interfere is within the set width range (83, 84). The center position of only the mark is registered in the f memory addressed to the mark (85).
[0090]
Next, the MPU 41 verifies whether the mark center point position data group written in the memory is the center point distribution corresponding to the mark distribution shown in FIG. 5, and sets the detection information of the r mark and the f mark as shown in FIG. Group correspondingly (90, 100). Here, data deviating from the mark distribution equivalent to that shown in FIG. 5 is deleted in units of sets, and only the data set corresponding to the mark distribution shown in FIG. If all are appropriate, 8 sets of data remain on the rear r side and 8 sets of data remain on the front f side.
[0091]
Next, the MPU 41 changes the center point position data of the first mark in each set after the second set to the first center point position of the first set (first set) of the data set on the rear r side. The center point position data of the second to eighth marks are also changed by the changed difference value. That is, the center point position data group of each set after the second set is changed to a value shifted in the y direction so that the top of each set is aligned with the top of the first set. Similarly, the center point position data in each set after the second set on the front f side is also changed.
[0092]
Refer to FIG. 8 again. The MPU 41 calculates average values Mar to Mhr (FIG. 14) of the center point position data of each mark of all sets on the rear r side by “calculation of average pattern” (MPA), and also calculates all the values on the front f side. Average values Maf to Mhf (FIG. 14) of the center point position data of each mark in the set are calculated. These average values are virtual average position marks distributed as shown in FIG.
MAkr (representative of Bk rear orthogonal mark),
MAyr (representative of Y rear orthogonal mark),
MAcr (representative of C rear orthogonal mark),
MAmr (representative of M rear orthogonal mark),
MBkr (representative of Bk rear diagonal mark),
MByr (representative of the Y rear oblique mark),
MBcr (representative of C rear oblique mark), and
MBmr (representative of M rear diagonal mark), and
MAkf (representative of Bk front orthogonal mark),
MAyf (representative of Y front orthogonal mark),
MAcf (representative of C front orthogonal mark),
MAmf (representative of M front orthogonal mark),
MBkf (representative of Bk front oblique mark),
MByf (representative of Y front oblique mark),
MBcf (representative of C front diagonal mark), and
,
MBmr (representative of M front diagonal mark)
The center point position of is shown.
[0093]
In the displacement amount calculation (DAC) shown in FIG. 8, the MPU 41 calculates the image formation displacement amount as follows. The calculation (Acy) of the image forming deviation amount of Y is specifically shown below.
[0094]
Sub-scanning deviation amount dyy:
Deviation amount of the difference (Mbr−Mar) in the center point position between the Bk orthogonal mark MAkr and the Y orthogonal mark MAyr on the rear r side with respect to the reference value d (FIG. 5)
dyy = (Mbr−Mar) −d.
[0095]
Main scanning deviation amount dxy:
Deviation amount with respect to the reference value 4d (FIG. 4) of the difference (Mfr−Mbr) in the center point position between the orthogonal mark MAyr on the rear r side and the oblique mark MByr
dxyr = (Mfr−Mbr) −4d
And the deviation of the difference (Mff−Mbf) between the center point positions of the orthogonal mark MAyf on the front f side and the oblique mark MByf with respect to the reference value 4d (FIG. 5)
dxyf = (Mff−Mbf) −4d
And average value

[0096]
Skew dSqy:
Difference in center point position between the orthogonal mark MAyr on the rear r side and the orthogonal mark MAyf on the front f side
dSqy = (Mbf−Mbr).
[0097]
Main scanning line length deviation amount dLxy:
A value obtained by subtracting the skew dSqy = (Mff−Mfr) from the difference (Mff−Mfr) of the center point position between the rear r side oblique mark MByr and the front f side oblique mark MByf.

[0098]
The other C and M image forming deviation amounts are calculated in the same manner as the calculation related to Y (Acc, Acm). Although Bk is generally the same, in this embodiment, since color matching in the sub-scanning direction y is based on Bk, the positional deviation amount dyk in the sub-scanning direction is not calculated for Bk (Ack). .
[0099]
In the shift adjustment (DAD) shown in FIG. 8, the MPU 41 adjusts the image formation shift amount of each color as follows. The Y shift amount adjustment (Ady) is specifically shown below.
[0100]
Adjustment of sub-scanning deviation amount dy:
The start timing of image exposure (latent image formation) for forming a Y toner image is set by shifting the calculated shift amount dyy from the reference timing (y direction).
[0101]
Adjustment of main scanning deviation amount dxy:
The transmission timing (x direction) of the image data at the head of the line to the exposure laser modulator of the writing unit 5 with respect to the line synchronization signal representing the head of the line in image exposure (latent image formation) for Y toner image formation It is set by shifting the calculated deviation amount dxy from the reference timing.
[0102]
Adjustment of skew dSqy:
The rear r side of the mirror extending in the x direction is supported by a fulcrum and the front f side of the writing unit 5 reflects the laser beam modulated by the Y image data facing the photosensitive drum 6b and projects it onto the photosensitive drum 6b. , And is supported by a block slidable in the y direction. The skew dSqy can be adjusted by moving this block forward and backward in the y direction by a y drive mechanism mainly composed of a pulse motor and a screw. In “adjustment of skew dSqy”, the pulse motor of this y driving mechanism is driven to drive the block from the reference y position by an amount corresponding to the calculated skew dSqy.
[0103]
Adjustment of main scanning line length deviation amount dLxy:
The frequency of the pixel synchronization clock for allocating image data in units of pixels on the line is set to reference frequency × Ls / (Ls + dLxy). Ls is the reference line length.
[0104]
The other adjustments of C and M image formation deviation amounts are adjusted in the same manner as the adjustment for Y (Adc, Adm). Although Bk is substantially the same, in this embodiment, since color matching in the sub-scanning direction y is based on Bk, the positional deviation amount dyk in the sub-scanning direction is not adjusted for Bk (Adk). . Until the next “color matching”, a color image is formed under the adjusted conditions.
[0105]
-Second Example-
The hardware configuration of the second embodiment is the same as that of the first embodiment described above. However, in the second embodiment, the MPU 41 performs “color matching” (CPA) shown in FIG. The contents of steps 31 to 37 in the “color matching” (CPA) are the same as those shown in FIG. In the second embodiment, when the execution number n of the “test pattern formation and measurement” PFM exceeds the set value d, the “test pattern formation and measurement” PFMa of the second mode is executed. In this PFMa, the mark is not touched with reference to the connection mark center point position obtained by “calculation of the mark center point position” in the “formation and measurement of test pattern” executed in advance. The connection mark does not come into contact with the mark to be made), and the formation of the mark is started at this timing, and on the transfer belt 10, as shown in FIG. 17, each of the rear r, the center c, and the front f A set of r mark, c mark and f mark including a start mark and 8 sets of test patterns is formed, and the marks are detected by the optical sensors 20r, 20c and 20f, and the mark detection signals Sdr, Sdc and Sdf are set to A / D converters 36r, 36c, and 36f convert it into digital data, that is, mark detection data Ddr, Ddc, and Ddf. Then, the center point position of the mark (Sdr, Sdc, Sdf) is calculated.
[0106]
In the next “pattern verification” SPCa, first, “r mark verification” calculates the y width of each r mark having a center position calculation value, and checks whether the y width is within the set width range. The center position of only the mark within the range is registered in the r memory addressed to the mark. The contents of “verification of r mark” are the same as the contents of “verification of f mark” described below.
[0107]
Next, referring to FIG. 16, the MPU 41 calculates the y width of each of the f marks having the center position calculation value (81, 82) in the “verification of f mark” (80), and this y width is within the set width range. The center position of only the mark within the set width range is registered in the f memory addressed to the mark (85).
[0108]
Further, the MPU 41 calculates the y width of each c mark having the center position calculation value in “c mark verification” (110) (111, 112), and checks whether this y width is within the set width range. (114) The center position of only the mark within the set width range is registered in the f memory addressed to the mark (115).
[0109]
Next, the MPU 41 verifies whether the mark center point position data group written in the r, c, f memory is a center point distribution corresponding to the mark distribution shown in FIG. 17, and the r mark, c mark, and f mark. The detection information is grouped in correspondence with the set shown in FIG. 17 (90, 100, 120). Here, data deviating from the mark distribution equivalent to that shown in FIG. 17 is deleted in units of sets, and only the data set corresponding to the mark distribution shown in FIG. If all are appropriate, 8 sets of data remain on the rear r side, 8 sets on the center c, and 8 sets on the front f side.
[0110]
Here, the MPU 41 checks whether the number of sets on the rear r side, the number of sets on the center c, and the number of sets on the front f side are within the set range (b to c) (33a).
(1) If both the number of sets on the rear r side and the number of sets on the front f side are within the setting range, the first mode designation information is generated, and the process proceeds to the next, and the same average pattern as in the first embodiment After the calculation and the calculation of the deviation amount are executed by MPAa and DACa, respectively, the process proceeds to the deviation adjustment DAD having the same contents as in the first embodiment.
(2) However, if the number of sets on the rear r side is out of the setting range and both the number of sets on the center c and front f sides are within the setting range, the second mode designation information is generated, and the process proceeds to the next, The calculation of the average pattern and the calculation of the deviation amount based on the mark set on the center c and the front f side are executed by MPAa and DACa, respectively, and then the process proceeds to the deviation adjustment DAD having the same contents as in the first embodiment.
(3) If the number of sets on the front r side is out of the setting range, and both the number of sets on the center c and the rear r side are within the setting range, the third mode designation information is generated, and the process proceeds to the next. Then, the calculation of the average pattern and the calculation of the deviation amount based on the mark set on the rear r side are executed by MPAa and DACa, respectively, and then the process proceeds to the deviation adjustment DAD having the same contents as in the first embodiment.
(4) When the number of mark sets of at least two of the rear r side, the center c, and the front side f is out of the setting range, the number n of “test pattern formation and measurement” is incremented by 1; Proceed to “Formation and measurement of test pattern” PFMa. However, when the number n reaches the set value i, data 1 prohibiting automatic color matching is written in the register FAP (38-36), and information indicating that the transfer belt is abnormal, cleaning or replacement is required is displayed on the operation board 610. Is displayed on the display device 615 (37). Then, the “color matching” CPA ends. In this case, color misregistration adjustment is not performed.
[0111]
【The invention's effect】
Since color matching is automatically executed not only when an instruction is input but also when a predetermined condition is satisfied, a color image without color misregistration can be formed stably. For example, when the mark detection accuracy is reduced due to deterioration of the mark forming surface, automatic start of color matching is limited, so that the time during which the color image forming apparatus cannot be used by the execution of color matching, that is, the downtime is prolonged. .
[Brief description of the drawings]
FIG. 1 is a front view showing an appearance of a full-color copying machine according to an embodiment of the present invention.
FIG. 2 is a block diagram showing an outline of an image data processing system of the color copying machine shown in FIG.
3 is an enlarged longitudinal sectional view showing an outline of an image forming mechanism of an image forming unit PTR of the printer 100 shown in FIGS. 1 and 2. FIG.
4 is a plan view of the transfer belt 10 shown in FIG. 2 and schematically shows each color mark formed on the surface thereof. FIG.
FIG. 5 is an enlarged plan view showing a distribution of marks formed on the transfer belt 10 shown in FIG.
6 is a block diagram showing a partial configuration of a process controller 131 shown in FIG.
7 is a flowchart showing an outline of print control of a microcomputer (MPU) 41 shown in FIG.
FIG. 8 is a flowchart showing an outline of a “color matching” CPA shown in FIG. 7;
FIG. 9 is a flowchart showing the contents of a “test pattern formation and measurement” PFM shown in FIG. 8;
FIG. 10 is a flowchart showing a part of the contents of the “pattern verification” SPC shown in FIG. 8;
FIG. 11 is a flowchart showing the remainder of the contents of the “pattern verification” SPC shown in FIG. 8;
12 is a plan view showing a distribution of color marks formed on the transfer belt 10 shown in FIG. 2, and a time chart showing a level change of a detection signal Sdr read from the color mark of the optical sensor 20r.
13A is an enlarged time chart showing a part of the time chart of the detection signal Sdr shown in FIG. 12, and FIG. 13B is an A / D conversion of the detection signal shown in FIG. 7 is a time chart showing only a range in which data is written in a FIFO memory inside the MPU 41 shown in FIG.
FIG. 14 shows average value data Mar,... Calculated by the “average pattern calculation” MPA shown in FIG. 8, and virtual marks MAkr,. It is a top view which shows the mark row | line | column represented.
FIG. 15 is a flowchart showing an outline of “color matching” CPA executed by the MPU 41 in the second embodiment of the present invention;
FIG. 16 is a flowchart showing a part of the contents of a “pattern verification” SPC executed by the MPU 41 in the second embodiment of the present invention;
FIG. 17 is an enlarged plan view showing the distribution of marks formed on the transfer belt in the second mode in the second embodiment of the present invention.
[Explanation of symbols]
5: Writing unit 6a to 6d: Photosensitive drum
7a-7d: Developer 8: Paper feed cassette
9: Driving roller 10: Transfer belt
11a to 11d: transfer device 12: fixing device
13a: Tension roller
13b: driven roller 20r, 20f, 20c: optical sensor
41: MPU (microcomputer)
400: Automatic document feeder
PC: Personal computer
311: Reading unit SBU: Sensor board unit

Claims (6)

Mark forming means for forming marks of respective colors in a standard area on a moving surface in a moving direction; a mark sensor for detecting marks of each color formed in the standard region; on the moving surface; A monitoring sensor that detects an image of a predetermined monitoring area defined outside the standard area; information obtained by removing a mark at a position corresponding to the position in the moving direction of the image detected by the monitoring sensor from the mark detection information of the mark sensor A color matching means for adjusting each color image formation timing so as to eliminate image formation deviation between colors; and color matching from the formation of the mark to the adjustment of each color image formation timing in response to an execution instruction input. A color image forming apparatus comprising: a control means that automatically starts when a predetermined condition is satisfied;
The color image forming apparatus according to claim 1, wherein when the number of images detected by the monitoring sensor is equal to or greater than a set value, the control unit restricts subsequent automatic start of color matching. Mark forming means for forming marks of respective colors in a standard area on a moving surface in a moving direction; a mark sensor for detecting marks of each color formed in the standard region; on the moving surface; A monitoring sensor that detects an image of a predetermined monitoring area defined outside the standard area; information obtained by removing a mark at a position corresponding to the position in the moving direction of the image detected by the monitoring sensor from the mark detection information of the mark sensor A color matching means for adjusting each color image formation timing so as to eliminate image formation deviation between colors; and color matching from the formation of the mark to the adjustment of each color image formation timing in response to an execution instruction input. A color image forming apparatus comprising: a control means that automatically starts when a predetermined condition is satisfied;
When the number of remaining marks removed based on the position in the moving direction of the image detected by the monitoring sensor from the mark detection information of the mark sensor is out of the setting range, the control unit restricts automatic start of subsequent color matching. And a color image forming apparatus. The standard area is each end area of the image exposure line in a direction orthogonal to the moving direction of the moving surface, and the monitoring area is a center area centered at the midpoint of the image exposure line; The color image forming apparatus according to claim 1, wherein the monitoring sensor is a single sensor that detects the central image. The control means, when the number of marks to be referred to in calculating the image forming deviation between colors is insufficient, the mark forming means forms marks of each color in each end region and the central region in a predetermined order at a predetermined distance; The mark formed in each end region and the center region is detected by the sensor and the monitoring sensor; the color matching means detects the mark between the colors based on the mark detection information of one end region and the center region where the detected number of marks is sufficient. The color image forming apparatus according to claim 3, wherein each color image forming timing is adjusted so as to eliminate image shift. The control means generates automatic start prohibition information when the condition for limiting the automatic start is satisfied, and the control means suspends automatic start when there is automatic start prohibition information. The color image forming apparatus according to any one of 1 to 4. At least one of the control means is established immediately after the color image forming apparatus is turned on, after the number of color image forming sheets exceeds a set value, and after the internal temperature of the color image forming apparatus changes by more than a set value. 6. The color image forming apparatus according to claim 5, wherein the color matching is activated on condition that there is no activation prohibition information.

Images